When water temperatures in the Eastern Equatorial Pacific, off the coast of Peru, are higher than usual, weather patterns around the world are affected. This phenomenon occurs erratically –every two to seven years- and during periods when ocean temperatures are particularly high the effects throughout the world can be alarming.
The El Niño warm ocean current gets its name from the time of year when it is usually first detected. It was the fishermen of the Peruvian town of Paita who in the 17th century first noticed that on occasion sea temperatures would rise and fish stocks disappear around Christmastime, when the birth of the Christ Child (“El Niño”) is celebrated by Christians.
During late 2015, unusually high winter temperatures directly attributable to the El Niño effect led to record levels of rainfall in Scotland and northern England, causing serious flooding and the evacuation of residents from more than 5000 homes.
The effects in the Entre Rios, Corrientes and Chaco frontier regions of Argentina, Paraguay, Brazil and Uruguay were even more devastating. Here, more than 150,000 people were displaced by flooding as heavy summer rains caused major rivers to burst their banks.
But the periodic disturbances caused by El Niño to the world’s ocean currents and therefore to its overall weather patterns can also lead to reduced rainfall in some areas, and even drought. Some historians have even linked the El Niño related severe droughts in Asia, Australia, Mexico, southern Africa and other parts of the world with the famine that contributed to the French Revolution in 1789.
In Peru, while heavy rains can be expected on the country’s normally arid desert coast during an El Niño year, causing damage to infrastructure and leading to crop failure, in the highland and tropical forest regions precipitation during what is normally the rainy season, from December to March, can often be reduced.
During the particularly severe El Niño phenomenon of 1998, the Amazon basin was hit by drought, with wildlife sightings around oxbow lakes and other water sources, including the Tambopata river basin, reported as much higher than usual, as animals emerged from the forests in search of water.